Phosphorylation of Thiophenes

This review deals with synthetic methods, chemical transformations, and some physical properties of thienyland benzothienyl substituted phosphorus compounds bearing P-Het or P-CH2-Het bonds. The basic synthetic approaches to these compounds include reactions of metalated thiophenes with phosphorus(III) and (V) halides, phosphorylation of thiophenes in the presence of a mild Lewis acid, use of halogenothiophenes in the Arbuzov reaction, and phosphorylation of thiophenes with phosphorus(III) halides in basic medium. Synthetic approaches to condensed heterocyclic systems of novel types are also considered. Investigation of chemical properties of phosphorylated thiophenes has revealed that, despite the great similarity with phenyl analogues, differences connected to the nature of the heterocycle are observed. The tertiary phosphines bearing at least one thienyl substituent are less active in quaternization and oxidation reactions. At the same time, basic hydrolysis leading to C-P bond cleavage is facilitated, as compared to benzene derivatives.